Huh... So Sabi is making his bet right now by saying that... It's actually a 50/50 decision... So let's consider some stuff...
1) His insiders: Soooo... Assuming they know who the fifth character is... Aren't they under NDA? Why would they casually break NDA to give some low-priority journalist what he wants to know? This is why I don't believe a single textual leaker that claims they got insiders...
2) Insiders, the Revenge: So, let's assume there are insiders... Why oh why they are willing to give info to some guy instead of doing it themselves and earn the fame? Do they owe Sabi a big favor and are doing these because of that? Sabi is paying for the info? (Very unlikely)
3) Sabi is wrong: What's going to happen when whatever info Sabi provides is not right? Has he apologized? Has he made a stupid excuse? Does he have the balls to admit he is wrong in, at least, one ocassion?
Sorry, but his words are meaningless to me, and this is the first time I see Sabi sweating balls wanting info on this leak, so right now, what I believe is, he made his decision... There's no insiders, just his common sense as the judge of what happens to a leak.